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Was there or is there life on Mars.? . And are extraterrestrial beings such as the tall whites etc.. Visit or even occupy this earth?

Robert Walker, Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.

Answered Jan 8, 2016

First there could well be microbes on Mars even now. Early on it was as habitable as Earth, possibly. It probably even had oceans as we can trace the ancient shoreline all the way around the Northern hemisphere, even with deltas. And it certainly had lakes, for instance filling Gale crater, at least temporarily. And we know now from Curiosity that the water was reasonably habitable - not too salty, acid, or alkali for life like life on Earth.

The main problem with Mars as a place for life to originate is that it was at its most habitable for perhaps only a few hundred million years. And then it got very cold. Probably most of the time the lakes and seas were ice covered. Think an Antarctic type world rather than a warm planet like Earth. And gradually lost most of its atmosphere. Except early on. Nowadays, even if it had an Earth pressure atmosphere, it would still be nearly as cold as Antarctica, or Siberia anyway, and would probably not be able to support much vegetation. That's because it gets only half the heat that the Earth does. And it's even worse, it has only a hundredth of the atmospheric pressure of Earth. So it is bitterly cold there. It's most habitable regions are like Antarctica, but at night, get so cold that even at the equator, it gets below the temperature where CO2 would begin to sublimate out of the atmosphere as dry ice, for many nights, every year. At the poles it has thick layers of dry ice.

So, that's how cold it gets. Though in the daytime in the equator it can sometimes get as hot on the surface as 30 C. It has a very shallow "permafrost layer" only a couple of cms deep. A couple of cms below the surface, even at the equator, it never gets above 0 C.

So - could life there have evolved as far as complex lifeforms, or just microbes? Well on Earth, then complex lifeforms like us, plants, everything you think of as life really except microbes - that all dates back to only half a billion years ago. So it took billions of years to get anything even as complex as the tiniest microscopic multicellular lifeforms.

If the pace of evolution was the same on Mars, it probably has microbes at most, and lichens maybe if you are very lucky.

It might have been seeded by life from Earth but that's not as easy as you'd think because only the largest impacts that hit Earth send material all the way to Mars and most of it takes millions of years to get there. Some material gets there within the first century of the impact - but anything that survives that would need to be very hardy, vacuum and cosmic radiation resistant, and also, able to survive in the extremely challenging habitats on Mars when it gets there. And for that matter, find those habitats. Almost anywhere on Earth you'll find a habitat of some sort. But much of Mars, today, may well be uninhabitable, with just a few spots here and there, oases for life, where small numbers of microbes can survive.

(Some think that there may be life in small numbers almost anywhere on Mars however, just saying for completeness, especially those who think that Viking discovered life on Mars already - it's not an impossible view, because life can make use of the 100% night time humidity, in Mars simulation experiments on Earth, even without liquid water, and it has morning frosts even in the equatorial regions - if somehow life can trap the water from the melting frosts before it gets back into the atmosphere, it could create its own microhabitats in that way).

There might all the same be some Earth lifeforms on Mars, of course evolved independently for at least tens of millions of years, but quite possibly for billions of years - on a very different planet.

There could also be native Mars lifeforms that evolved there. Even if just microbes, well the machinery of life is immensely complex. If independently evolved, no reason it needs to use DNA. If it does use DNA then the translation machinery that turns it into messenger RNA bound to be different, at least in detail, as on Earth it is immensely complicated, various forms of error correction etc, so why would it be identical to that if independently evolved?

Or it might just use RNA throughout and not bother with DNA as some think the earliest lifeforms on Earth did. Also, instead of the bulky ribosomes that convert RNA into proteins, it could use ribozymes which are made of RNA only which permits much smaller microbes - in theory anyway. Or might use some other form of "XNA" such as PNA which is more robust than DNA. Many ideas there.

And then - even if based on RNA, it might use different bases from Earth life. Might be mirror life.

Or if the bases are all the same as for Earth life, there could be differences in the translation table that it uses to convert the information in the messenger RNA into amino acids to make proteins.

Indeed seems quite likely if independently evolved that there is some difference somewhere in all that complex machinery.

Or it could be identical in all respects, except, say, that it has a more efficient metabolism. Or that it has a different, maybe better, way of doing photosynthesis (Earth life has at least three significantly different ways of doing photosynthesis - Mars life even based on DNA perhaps might use a fourth method never explored on Earth).

For microbiologists, it would be just immensely fascinating. And this is a form of nanotechnology. Think of all the things we use that are made using lifeforms on Earth? Now imagine if we had some independently evolved life from Mars. It could be quite revolutionary, and surely one of the greatest discoveries in biology.

Also needs great care, can we safely bring such a different lifeform back to Earth? Maybe it is best studied "in situ" on Mars first. If we do find this life there.

As for intelligent creatures, or indeed complex lifeforms - the analogy with Earth suggests it is unlikely that there is anything much more than microbes. But you can put forward an argument in the other direction.

The thing is that on Earth modern multicellular life evolved immediately after a time of great stress, when the planet was almost entirely covered in ice. This is something that happened to Mars probably many more times than for Earth.

One big difference is its at times highly elliptical orbit. Unlike Earth its eccentricity is continually changing, sometimes almost circular, sometimes very elliptical for a terrestrial planet with the result that one hemisphere has much more extreme seasons than the other, and the total amount of light and heat on the planet varies a lot. It might have an ocean covered with an ice sheet that melted and then froze again even as frequently as every two years.

So what does that do to evolution? Does it slow it down? Or maybe, does it speed it up? Was evolution on Earth slower because we had things so good here, so that microbes could just laze around not changing much sometimes for hundreds of millions of years?

If it speeds it up a lot, then might Mars have had plants and complex life early on?

It's really hard to evaluate this, because with only one example of evolution on Earth, we really have no idea how much evolution can vary on other planets. Earth may be typical, or it may be very unusual in various ways. We have no way of knowing.

And - it's now thought by some astronomers, that Mars did have oxygen in its early atmosphere. Maybe not a huge amount but some percentage of oxygen, which is why it ended up being rust red all over. So that also adds to the possibility of complex life, if there was some oxygen they could use, even if much less than on Earth.

But if Mars did have intelligent life there - I'm including things like modern octopuses and squids there - it's surely all gone now. Well - except for some very exotic form of life. Hard to imagine a habitat that is sufficiently rich and complex to sustain complex energy demanding lifeforms on present day Mars. Even on Earth, with all its complex lifeforms, the habitats most like the Mars surface have only microbes, green algae, or occasionally lichens, and no complex lifeforms at all. Not in the most arid, dry, harsh regions that are most similar to Mars.

The only place complex "intelligent" life, at least of the type we have on Earth, could exist is underground.

Mars is geologically similar to Earth with a molten core, and though the surface is cold, temperature rises below the surface. The main difference is that Mars has no continental drift, which is why its few volcanoes grew so very large. And it's still geologically active, though not nearly so much as Earth.

Mars is apparently still volcanically active, in the geologically recent past, and expected to be so again in the future from time to time - and has had occasional lakes, of many cubic kilometers of water due to geological activity - even in the geologically recent past - it's not very active. There is no known present day activity. There might be hot spots and even at a stretch, ice fumaroles not detectable from orbit. Maybe they permit underground water bodies. But it doesn't seem likely - at present anyway - that it has seas underground, or the likes of huge lakes down there. It would be a huge surprise if it does.

It could have a "hydrosphere" very deep down, kilometers down - rock saturated with water and heated from its interior. But again - others think if it has a hydrosphere, it probably has not much water left in it any more. Even the most optimistic there put depths of perhaps of order 100 meters or so of water kilometers below the surface. If it exists, that would be a lot of water on Mars, and a major habitat. It could be, if it is inhabited, the main place where life exists on Mars at least by abundance. But it doesn't seem a likely spot for intelligent life. Maybe if it developed multicellularity, some worm like creatures?

There may be water within cms of the surface in places, just 1 or 2 cms below the surface. But this is habitat expected to be mms thick, and the thickest ones could be of order a cm or so thick. Again not the best place for intelligent life, unless very exotic (sentient lichens??)

As for beings with technology - we can pretty much rule them out. Because our orbiters can observe the surface on well sub meter scales. Better resolution than for the Moon. We would easily see tracks of vehicles and other signs of intelligent life there. Unless you posit that they continually sweep the surface behind them as they move, in order to hide all traces of their presence.

We'd also see traces of herds of animals - which in any case seem impossible because the atmosphere is a near vacuum.

In any case, it's very unlikely that they developed technology equivalent to Earth and then never came to Earth. Obviously if they have it now, they developed it billions of years ago when the planet was more hospitable - how likely is it they would develop it just now? So then why are they not here, why didn't they come to Earth back then when it was much easier, with their technology at its height on a flourishing planet? And if they did come here, why aren't they still here, or did they not like Earth? They would surely have brought complex multicellular life with them.

Unless they were conservationists and stayed on Mars because they wanted to leave Earth, even though only inhabited by microbes, to its own devices, and would rather die on their cold and arid world than interfere with the development of Earth. I suppose that's not impossible. The range of ideas ETs could have is probably far greater than the range of ideas humans have, and so anything a human could dream up almost, is probably a possible belief system for ETs along with many other ideas we can't even think of.

But - I don't think we are going to find technology on Mars myself. At least - would put that right down at the bottom of the list of possibilitites.

For intelligent - non technological life - we could find that on Mars, but if so - well my guess is that it is probably long extinct, leaving only microbes, lichens and such like similar to comparable habitats on EArth.

But we could potentially find intelligent life in the Europa ocean. Where by intelligent I mean anything from e.g. squid / octopus intelligence - or even - sea anemones, worms and so on have a kind of an intelligence - all the way up to maybe an intelligence that is more mature and keener than what we have ourselves. No reason for them to be evolved to exactly same stage of evolution as us. Seems very unlikely. So could be like whatever we might evolve into a few hundred million years into the future, or like our distant past a few hundred million years ago, or some other direction not explored on Earth at all.

I think Europa is our best bet in our solar system to find some form of intelligent life, because it has an oxygen rich ocean. And if there is intelligence there, even human level or more evolved, then without technology, which would be very hard to develop in an ocean without fire, they would not even know that anything exists outside of their totally ice covered ocean. Separated by 100 kilometers of ice from the rest of the solar system.

I think we need to be especially careful, exploring Europa, not to introduce Earth microbes there. Because they could totally disrupt the ecosystem there. Or whatever there is, even might be like the earliest Earth life precursors, not yet evolved to robust modern life, RNA based for instance, no DNA at all, far smaller than any modern living cell on Earth. It might be very vulnerable to even a single microbe of modern Earth based life.

I think we should be careful not to send even a single Earth microbe to Europa until we know for sure what we are dealing with there, or at least a lot more than we do now. For that reason I think it is premature to plan a lander on Europa, unless we can either guarantee it to be 100% sterile, or guarantee that it can't contact the subsurface Europa ocean or other potential habitats vulnerable to Earth life there.

Even dead Earth life, even a package of DNA and other bits of a modern cell could be enough to change Europa, if there is some way it can get into the subsurface ocean from its surface.

What we might be able to do is to send an orbiter to fly through plumes of water geysering up from the interior of Europa 100 kms below. If so that would be awesome and would give a way to sample the subsurface oceans with almost no risk of introducing Earth life there.

Meanwhile maybe we can learn how to achieve 100% sterilization. It's possible by heat treatment - the only problem there is, that 100% sterile spacecraft would be so damaged it would no longer be able to function as a spacecraft, because our electronics and instruments are vulnerable to the same levels of heat that sterilize them. But there are many ideas for ways to sterilize spacecraft, and who knows, maybe some time in the next couple of decades we will achieve 100% sterile spacecraft.

BTW another way spacecraft could be 100% sterile is if they are made in space, say from asteroid material, in conditions that are 100% sterile throughout, so no life is introduced to them in the first place. But that's not achievable at present and is pretty much in the realms of fantasy right now, sadly.

One of the most promising developments is supercritical CO2 snow, which is great for getting rid of not only microbes, but also dead organics as well, which I htink you need to do to explore a place like Europa. But whether that can be 100% sterile I don't know.

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